In small doses, like those contained in the gum, nicotine is generally considered safe. But it does have stimulant properties that can raise blood pressure, increase heart rate and constrict blood vessels. One large report from 2010 found that compared to people given a placebo, those who used nicotine replacement therapies had a higher risk of heart palpitations and chest pains.
That’s one reason that nicotine gum should, ideally, be used for no more than four to six months, said Lauren Indorf, a nurse practitioner with the Cleveland Clinic’s Tobacco Treatment Center. Yet up to 10 percent of people use it for longer periods, in some cases for a decade or more she said.
Some research has raised speculation that long-term use of nicotine might also raise the risk of cancer, though it has mostly involved laboratory and animal research, and there have not been any long-term randomized studies specifically addressing this question in people.